libstdc++: suppress -Wdangling-reference with operator| [PR111410]

It seems to me that we should exclude std::ranges::views::__adaptor::operator|
from the -Wdangling-reference warning.  It's commonly used when handling
ranges.

	PR c++/111410

libstdc++-v3/ChangeLog:

	* include/std/ranges: Add #pragma to disable -Wdangling-reference with
	std::ranges::views::__adaptor::operator|.

gcc/testsuite/ChangeLog:

	* g++.dg/warn/Wdangling-reference17.C: New test.

1 files changed, 15 insertions, 0 deletions

diff --git a/gcc/testsuite/g++.dg/warn/Wdangling-reference17.C b/gcc/testsuite/g++.dg/warn/Wdangling-reference17.C
new file mode 100644
index 0000000..2236984
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wdangling-reference17.C
@@ -0,0 +1,15 @@
+// PR c++/111410
+// { dg-do compile { target c++20 } }
+// { dg-options "-Wdangling-reference" }
+
+#include <vector>
+#include <ranges>
+
+int main()
+{
+  std::vector v{1, 2, 3, 4, 5};
+  for (auto i : std::span{v} | std::views::take(1))
+    {
+      (void) i;
+    }
+}